[sorry about the late delay...]
I don't haven't been following the entire thread here, so this may have been previously explained. The reason the reply goes to the originator and not the list is because a long time ago some network vandal repeatedly set up an automatic reflector which caused messages posted to SLE to be responded to.
That happens but there are easier ways to deal with stuff like that. The real reason that the list behavior is this way is because, well, that's the correct behavior. When people complain about this, it's generally because they are using a broken mail reader that doesn't distinguish between a reply and group reply. The best discussion of this can be found here: http://www.unicom.com/pw/reply-to-harmful.html -- -ckm